The leading cause of morbidity and mortality in SLE patients remains glomerulonephritis. It would be helpful to have a method of predicting when patients were going to have a flare of their renal disease so that it might be treated before significant damage occurred. Anti-DNA antibody appears to play a significant role in the pathogenesis of SLE glomerulonephritis. But not all patients with anti-DNA antibody have concomitant nephritis. This project looks at several qualities of anti-DNA antibodies that may help to determine which antibodies have pathogenic potential. The qualities to be looked at are the unusual phenomena of substrate competition, valence and avidity. Substrate competition refers to the ability of some anti-DNA antibodies to effectively compete with the enzyme DNA'se I for the substrate DNA. This property as well as the valence and avidity of SLE sera will be correlated with disease activity and with one another. Finally, the effect of high dose short term steroid dosage will be assessed with respect to whether and/or how rapidly it changes the above serologic findings.